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The Cause…or the “What” of What Works?. David S. Cordray Vanderbilt University IES Research Conference Washington, DC June 16, 2006. Treatment Strength. Outcome . .45 .40 .35 .30 .25 .20 .15 .10 .05 .00. 100 90 85 80 75 70 65 60 55 50 . T .
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The Cause…or the “What” of What Works? David S. Cordray Vanderbilt University IES Research Conference Washington, DC June 16, 2006
Treatment Strength Outcome .45 .40 .35 .30 .25 .20 .15 .10 .05 .00 100 90 85 80 75 70 65 60 55 50 T Infidelity t Achieved Relative Strength =.15 (85)-(70) = 15 C C “Infidelity” Expected Relative Strength =.25
Intervention Fidelity Intervention Fidelity Intervention, as conceptualized (T and C) Does the intervention, as implemented, faithfully represents the intervention“theory” or model? Intervention, as realized or implemented (t and c)
Dimensions Intervention Fidelity • Adherence to the intervention model: • Essential components (activities, processes) • Necessary, but not unique, activities, processes and structures (supporting the essential components of T) • Ordinary features of the setting (shared with C); • Quality of delivery (adherence); and • Receipt essential components.
Fidelity and IES Goals • Goal 2 (Development) • Need explicit model of the final intervention model • Products: • Evidence of potential effects, • an intervention model, • all relevant materials, and • detailed indices for assessing fidelity • Goals 3 (Efficacy) and 4 (Scale-up) • Need detailed indices of fidelity for: • training and program research (e.g., effects of core components) and • Need efficient indices for scaling implementation in the unit of delivery • Need efficient indices of fidelity in all conditions (T and C) • “Goal 6” – Managing the tension between fidelity and inevitable adaptation
Substantial Challenges • Developing explicit enough program models so the fidelity can be meaningfully assessed; • Measuring fidelity entails: • Multiple indicators • Mixed methods; • Constructing indexes: • Differential weighting of components • Use of broader range of scale construction procedures (cumulative and rubric-based); • Validation studies; • Because fidelity plays many roles, we’ll need multiple versions of fidelity scales (e.g, “scale-down”)
The Cause…and “What Works?” • In experimental research, the causal agent is a relative difference between ingredients in T and C conditions; • The achieved relative strength of the contrast is affected by infidelity; and • With adequate indices of fidelity, we can move to questions of what works, under what circumstances, and why.